DIFFERENTIATING RAPISTS AND NON-OFFENDERS USING THE RAPE INDEX

Some studies have suggested that phallometrically derived rape indices can differentiate groups of rapists and non-offenders. There are othe r studies however which cast doubt on this assertion, at least in so f ar as it applies to all but those few rapists who are sadistic. These studies have used rape indices which are derived from rapists' sexual responses to audiotaped descriptions of mutually consenting sex and br utal sexual assaults. It was hypothesized however, that stimuli which put more emphasis on the degrading and humiliating elements of rape wo uld improve discriminability. Stimuli were compiled to test this hypot hesis. The results indicate that neither rape indices derived from the physically brutal elements nor the degrading elements of rape were ab le to discriminate between rapists and non-offenders. Furthermore, the se indices were not related to offence histories. The results are disc ussed in terms of their implications for the assessment of rapists and theoretical considerations of their behaviour.